The present invention relates to a seal structure for hermetically enclosing the developer or toner for use in the developing device incorporated in image forming apparatus such as copying machines and facsimile systems before the device is placed into use.
The developing devices installed in such image forming apparatus are sometimes filled with unused developer or toner (herein referred to collectively as "developer") in advance. The developer accommodated in the device must be sealed off so as not to deteriorate before use. Generally, the developing device is internally provided with a developer chamber, and the opening of the developer chamber is closed, for example, with a filmlike seal member to hermetically enclose the developer therein. With some developing devices, the developer chamber is in the form of a cartridge removably attached to the device, and the opening of the cartridge is similarly closed with a seal member. In the case where the developer is thus hermetically accommodated within the developing device, the seal member is pulled out from outside the device immediately before use.
However, since the periphery of the seal member is affixed, over the entire width thereof (transverse to the developing device), to the housing of the device, it is difficult to remove the seal member even if it is pulled in a direction perpendicular to the widthwise direction. The seal member is effectively removable when pulled obliquely. With reference to FIG. 9 showing a conventional method of removing a seal member 102 from a developing device 101, it is difficult to remove the seal member 102 by pulling the member longitudinally of the device (in the direction of arrow X). It has been found that the seal member 102 can be removed gradually from one end thereof with a relatively small force by pulling the member in an oblique direction (the direction of arrow Xl) containing a component of the longitudinal direction and a component of the transverse direction with respect to the developing device.
Nevertheless, when the seal member 102 is pulled in this way, the following troubles will result.
(1) The pulling direction in which the seal member is easily removable, although recognized by the manufacturer, is not known to the user who actually handles the seal member, so that the seal member is not always removable easily. Further it is cumbersome to make reference to the instruction book or rely on the serviceman for the removal of the seal member.
(2) When the seal member 102 is pulled, the end portion thereof not positioned at the center of pull (the end positioned inside the developing device 101) is subjected to almost none of the pulling force but is in a free state, so that the seal member is liable to crease inside the developing device when pulled. The developer is likely to spill from the device if the seal member 102 is pulled out in its entirety with a portion of the developer held between such creases.
(3) Since the seal member 102 is pulled aside obliquely, the member becomes slack at its edge portion on the pulled side as seen in FIG. 9. It is then likely that the slack portion will be caught by some other part, making it difficult to pull out the seal member or breaking the member.
(4) To be smoothly removable, the seal member 102 preferably has an elongated leading portion (to be grasped by the hand) extending outward from the developing device 101, whereas the leading portion, if elongated, becomes an obstacle when the device 101 is to be set in the image forming apparatus and is likely to become easily caught by some parts of the apparatus. The leading portion may be folded, but the above drawback can not be overcome unless the folded portion is entirely fastened, for example, to an outside portion of the developing device with a specific elaborate means. Moreover, the folded portion must be separated off the device by a cumbersome procedure when the seal member is to be removed.
(5) To be readily removable, the seal member 102 is generally folded at an intermediate portion, therefore consists of the folded portion and the other portion to be pulled (pull portion) and is installed inside the developing device with the pull portion only extending outward from the device. When the developing device is adapted for use with a two-component developer and has in its interior a developer compartment and a toner compartment which are closed with the single seal member 102 with developer and toner accommodated in the respective compartments, the forward end of the pull portion is likely to be caught by a developer scraper inside the device or by the partition between the two compartments to result in a break of the member.